This invention relates to a tufting technique in which a pile of tufted carpet is formed from a pile yarn inserted with a needle into the backing fabric and fastened with a looper.
On a tufting machine the backing fabric is fed continuously and straightway in the stitching direction so that a series of piles of each pile yarn is formed alining straightway in the stitching direction.
According to the prior art, a colored pattern on the pile surface is produced by varying the length or amount of pile yarn fed to the needle in every needle stroke cycle, and by stiching selectively the needles into the backing fabric in every needle stroke cycle.
In U.S. Pat. Nos. 3,016,029, 3,067,701, 3,272,163, 3,433,188 and 3,435,787, there are disclosed pattern apparatuses composed of a feed roller for varying the length of pile yarn fed to the needle and a pattern control apparatus for actuating the feed roller.
According to these pattern apparatuses, a pattern classified with two colors is duplicated on the surface of tufted carpet by alternately threading a plurality of pairs of pile yarns respectively of different color into a plurality of needles lateraly alined, and by controling the length of these yarns fed in every needle stroke cycle in a manner to increase the length of one of each pair of pile yarns to form a high pile and to decrease the length of another of each pair of pile yarns to form a low pile to be hid under the high pile formed adjacent to it.
In U.S. Pat. Nos. 3,056,364, 3,177,833, and 3,547,058, Japanese Patent publications No. sho 46-14227, No. sho 54-10905, and No. sho 57-43662, and Japanese Laid-Opens No. sho 59-179863, No. sho 60-39466, No. sho 60-88166, No. sho 63-13553, there are disclosed other kinds of pattern apparatuses for driving a plurality of needles by selecting, in every needle stroke cycle, whether to insert into the backing fabric or not.
According to these pattern apparatuses, a pattern classified in two colors is duplicated on the pile surface by alternately threading two kinds of pile yarns colored respectively in different colors into a plurality of needles lateraly aligned, by selecting one of each pair of two needles adjacent to each other in every needle stroke cycle, and by stitching the selected one of each pair of two needles into the backing fabric to form piles.
This kind of tufting machines, comprising a pattern control means and a needle select means adapted to duplicate a pattern on the pile surface by selectively inserting each needle into the backing fabric in every needle stroke cycle, are sold by Cobble Tufting Machine Company in Sakai-city, Osaka, Japan.
According to the prior art, it is possible to duplicate a pattern classified in two colors, but it is impossible to duplicate more colorful and various patterns such as Wilton type carpets and Axminster type carpets.
In U.S. Pat. Nos. 3,026,830, 3,396,687, 3,203,388, 3,393,654, and 3,577,943, there is disclosed shift apparatuses for zig-zag tufting a series of piles in the stitching direction by laterally shifting a needle or the backing fabric in every needle stroke cycle.
The shift apparatuses are applied to the tufting machine as a means for avoiding an unsightly stripe, which is one kind of fault caused by unevenness in color or thickness of pile yarn, from the pile surface, and for drawing a comparatively simple pattern, such as pepper-salt pattern, on the pile surface. But, a relatively wide variety pattern could not be drawn with the shift apparatus.
Further, in accordance with the prior art, if the shift apparatus had been applied to the tufting machine together with the above pattern apparatuses to duplicate a classified pattern on the pile surface, the contour line of the pattern would be drawn in a zig-zag line and would become indistinct.
As a result, the shift apparatus had not been used applied together with the pattern apparatus for duplicating a pattern to be made in two colors.